硝基苯低温厌氧降解微生物的分离与筛选及降解机理的研究

发布时间：2018-12-16 23:16

【摘要】：硝基苯是苦杏仁味的淡黄色有机物,有剧毒性,易挥发,密度比水大,且具有稳定性,一旦进入环境中就很难被降解。硝基苯是一种常见的化工原料,随着工业废水的排放,对人体健康和水环境造成了严重的威胁,硝基苯已经出现在多个国家或组织列出的水体优先控制污染物的名单中,因此采用适当的处理工艺将硝基苯彻底降解,或者将其浓度降低到国家规定排放标准是我们需要解决的环境问题之一。本实验以硝基苯为目标污染物,以渭河西安市草滩段底泥中微生物混合微生物菌为菌种源,以硝基苯为唯一碳源,在低温(12℃)的条件下,pH值为7,通过逐渐递增硝基苯浓度的方式对菌种进行厌氧培养驯化,从驯化成熟后的驯化液中分离纯化出四种硝基苯降解菌株(分别命名为W1、W2、W3、W4)。通过对4种硝基苯降解菌株筛选实验表明,在硝基苯浓度为20mg/L,经降解9天后,其降解率分别为84.26%、89.78%、81.66%和93.82%。通过筛选实验得出W4菌株为硝基苯优势菌株。根据形态特征、革兰氏染色、生理生化试验结果,结合《伯爵氏细菌鉴定手册》可初步鉴定菌株W4为和杰氏棒杆菌。在温度为12℃的厌氧条件下,以pH值、硝基苯初始浓度、微生物接种量、不同碳源、不同氮源为影响因子对优势菌株W4进行降解特性研究,结果表明,菌株降解硝基苯最优化条件是:pH为7、微生物接种量为15ml、硝基苯初始浓度为16.93mg/L;在最优化条件对硝基苯低温厌氧降解9天,其降解率可达到97.91%。同时通过气-质联用仪对降解产物进行定性分析,其主要产物为苯胺、醛类、酮类和醇类物质,推测出可能的降解途径是:首先硝基苯通过还原作用生成亚硝基苯、苯胺,再通过微生物合成的降解酶使得苯环开环,生成低毒或无毒的醇类、酸类和酮类等有机物,最后进一步矿化为CO_2和H_2O。
[Abstract]:Nitrobenzene is a yellowish organic substance with bitter almond flavor, which is highly toxic, volatile, more dense than water, and stable. Once it enters the environment, it is difficult to be degraded. Nitrobenzene is a common chemical raw material. With the discharge of industrial wastewater, it poses a serious threat to human health and water environment. Therefore, it is one of the environmental problems that we should solve the environmental problems that we need to solve by adopting proper treatment process to completely degrade nitrobenzene or to reduce its concentration to the national emission standard. In this experiment, nitrobenzene was used as the target pollutant, mixed microorganism bacteria in the sediment of Caotan section of Weihe River as the source, nitrobenzene as the sole carbon source, and the pH value was 7 at low temperature (12 鈩，

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